Public defence in civil engineering, Farid Alinejad, M.Sc.
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Modeling the details of in-depth thermal radiation transfer in condensed materials for fire simulations
In this study, our main objective was to accurately model the penetration of thermal radiation within condensed materials to identify the optimal thermal radiation details required for fire simulations. To achieve this, we developed two novel methods for the condensed materials: a global spectral method (separated full spectrum k-distribution method) and a new interface treatment method (ordinate weighting method). The input for these methods is the optical constants, which we measured for black PMMA using spectroscopy techniques in a wide wavelength region of 0.25-25 μm.
We simulated the gasification of black PMMA for various heat fluxes using our developed methods and the gathered data. Our findings indicated that by utilizing a gray method with a depth and source temperature-dependent absorption coefficient, a two-flux method as radiative transfer equation solution method, and diffuse interface with equivalent reflectivities calculated from Fresnel relations, we could obtain optimal details of thermal radiation.
We recommend employing the identified thermal radiation details in fire simulations using open-source software, such as fire dynamics simulator (FDS). Our study demonstrated that our new methods made a significant difference compared to conventional methods in pyrolysis modeling of thermoplastics such as black PMMA.
Opponent: PhD, Research Director Frédéric André, University of Lyon, France
Custos: Professor Simo Hostikka, Aalto University School of Engineering, Department of Civil Engineering
Contact information of the doctoral student: Farid Alinejad, farid.alinejadalmachovan@aalto.fi, +358504782188
The public defence will be organised on campus (auditorium R1, Rakentajanaukio 4) and it can also be followed via Zoom.
The thesis is publicly displayed 10 days before the defence in the publication archive Aaltodoc of Aalto University.